Gerd Hoffmann wrote:
On 04/20/09 10:26, Avi Kivity wrote:
Gerd Hoffmann wrote:
The xen pv-on-hvm drivers use an msr to indicate "please place the
hypercall page here". Handling that in kernel isn't an option IMHO.
The contents of the hypercall page are vendor specific. This can be
handled from userspace (though ideally we'd abstract the cpu vendor
away).
Well, xenner doesn't do vmcalls, so the page isn't vendor specific.
Well, for true pv (not pv-on-hvm) it wouldn't use the MSR, would it?
It looks different for 32bit / 64bit guests though. And it actually
can be multiple pages (with one msr write per page). So the interface
for in-kernel handling would be more complex than "here is a hypercall
page for you".
To different MSRs, or multiple writes to the same MSR?
> The Hyper-V hypercall page is more problematic, as it's specified to
> be an overlay; the page doesn't have to exist in guest RAM.
In userspace it should be easy to handle though as qemu can just
create a new memory slot, right?
It depends if the MSR may be considered global, or is required to be
per-cpu. Need to refresh my memory on this, but I remember reading this
and saying 'yuck'.
--
error compiling committee.c: too many arguments to function
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